Physics-informed machine learning for inorganic scintillator discovery.

Applications of inorganic scintillators-activated with lanthanide dopants, such as Ce and Eu-are found in diverse fields. As a strict requirement to exhibit scintillation, the 4f ground state (with the electronic configuration of [Xe]4fn 5d0) and 5d1 lowest excited state (with the electronic configuration of [Xe]4fn-1 5d1) levels induced by the activator must lie within the host bandgap. Here we introduce a new machine learning (ML) based search strategy for high-throughput chemical space explorations to discover and design novel inorganic scintillators. Building upon well-known physics-based chemical trends for the host dependent electron binding energies within the 4f and 5d1 energy levels of lanthanide ions and available experimental data, the developed ML model-coupled with knowledge of the vacuum referred valence and conduction band edges computed from first principles-can rapidly and reliably estimate the relative positions of the activator's energy levels relative to the valence and conduction band edges of any given host chemistry. Using perovskite oxides and elpasolite halides as examples, the presented approach has been demonstrated to be able to (i) capture systematic chemical trends across host chemistries and (ii) effectively screen promising compounds in a high-throughput manner. While a number of other application-specific performance requirements need to be considered for a viable scintillator, the scheme developed here can be a practically useful tool to systematically down-select the most promising candidate materials in a first line of screening for a subsequent in-depth investigation.

Role of antisite disorder on preamorphization swelling in titanate pyrochlores.

Ion irradiation experiments and atomistic simulations were used to demonstrate that irradiation-induced lattice swelling in a complex oxide, Lu2Ti2O7, is due initially to the formation of cation antisite defects. X-ray diffraction revealed that cation antisite formation correlates directly with lattice swelling and indicates that the volume per antisite pair is approximately 12 Å3. First principles calculations revealed that lattice swelling is best explained by cation antisite defects. Temperature accelerated dynamics simulations indicate that cation Frenkel defects are metastable and decay to form antisite defects.

Kondo quasiparticle dynamics observed by resonant inelastic x-ray scattering.

Effective models focused on pertinent low-energy degrees of freedom have substantially contributed to our qualitative understanding of quantum materials. An iconic example, the Kondo model, was key to demonstrating that the rich phase diagrams of correlated metals originate from the interplay of localized and itinerant electrons. Modern electronic structure calculations suggest that to achieve quantitative material-specific models, accurate consideration of the crystal field and spin-orbit interactions is imperative. This poses the question of how local high-energy degrees of freedom become incorporated into a collective electronic state. Here, we use resonant inelastic x-ray scattering (RIXS) on CePd3 to clarify the fate of all relevant energy scales. We find that even spin-orbit excited states acquire pronounced momentum-dependence at low temperature-the telltale sign of hybridization with the underlying metallic state. Our results demonstrate how localized electronic degrees of freedom endow correlated metals with new properties, which is critical for a microscopic understanding of superconducting, electronic nematic, and topological states.

Itinerant spin excitations near the hidden order transition in URu(2)Si(2).

By means of neutron scattering we show that the high temperature precursor to the hidden order state of the heavy fermion superconductor URu(2)Si(2) exhibits heavily damped incommensurate paramagnons whose strong energy dispersion is very similar to that of the long-lived longitudinal f spin excitations that appear below T(0). This suggests that there is a strongly hybridized character to the itinerant excitations observed previously above the hidden order transition. Here we present evidence that the itinerant excitations, like those in chromium, are due to Fermi surface nesting of hole and electron pockets; hence the hidden order phase probably originates from a Fermi surface instability. We identify wavevectors that span nested regions of a f-d hybridized band calculation and that match the neutron spin crossover from incommensurate to commensurate on approach to the hidden order phase.

Quantum critical fluctuations in the heavy fermion compound Ce(Ni0.935Pd0.065)2Ge2.

Electric resistivity, specific heat, magnetic susceptibility, and inelastic neutron scattering experiments were performed on a single crystal of the heavy fermion compound Ce(Ni0.935Pd0.065)2Ge2 in order to study the spin fluctuations near an antiferromagnetic (AF) quantum critical point (QCP). The resistivity and the specific heat coefficient for T ⩽ 1 K exhibit the power law behavior expected for a 3D itinerant AF QCP (ρ(T) ∼ T(3/2) and γ(T) ∼ γ0 - bT(1/2)). However, for 2 ⩽ T ⩽ 10 K, the susceptibility and specific heat vary as log T and the resistivity varies linearly with temperature. Furthermore, despite the fact that the resistivity and specific heat exhibit the non-Fermi liquid behavior expected at a QCP, the correlation length, correlation time, and staggered susceptibility of the spin fluctuations remain finite at low temperature. We suggest that these deviations from the divergent behavior expected for a QCP may result from alloy disorder.

Lercanidipine: a review of its use in hypertension.

UNLABELLED: Lercanidipine is a vasoselective dihydropyridine calcium antagonist which causes systemic vasodilation by blocking the influx of calcium ions through L-type calcium channels in cell membranes. It is a highly lipophilic drug and as such has a slower onset and longer duration of action than a number of other calcium antagonists. Preclinical evidence suggests that lercanidipine has antiatherogenic potential and it may also protect against end-organ damage. In well controlled clinical studies, once daily administration of lercanidipine 10 or 20mg effectively reduced blood pressure (BP) compared with placebo in patients with mild to moderate hypertension without affecting heart rate. Response rate (percentage of patients with diastolic BP < or =90mm Hg or reduced by > or =10mm Hg from baseline) ranged from 50 to 66% with lercanidipine 10 mg/day and up to 86% with lercanidipine 20 mg/day. The drug had a long duration of action: clinical measurements for diastolic BP yielded a trough/peak ratio of >0.8 for both lercanidipine dosages in 1 study. Comparative trials, either published in full or as abstracts, found lercanidipine 10mg once daily for > or =4 weeks to be at least as effective as atenolol 50mg once daily, candesartan cilexetil 16 mg/day, captopril 25mg twice daily, enalapril 20 mg/day, hydrochlorothiazide 12.5mg once daily, irbesartan 150 mg/day and slow release nifedipine 20mg twice daily in patients with mild to moderate hypertension. In addition, lercanidipine 20 mg/day was as effective as amlodipine 10 mg/day. Lercanidipine is effective in the treatment of elderly patients (aged 60 to 85 years) with mild to moderate essential hypertension and in those with isolated systolic hypertension. In addition, monotherapy with lercanidipine 20 or 40 mg/day has shown efficacy in patients with severe hypertension, and add-on therapy helped control BP in a large proportion of patients with severe hypertension not responding sufficiently to beta-blockers, diuretics or ACE inhibitors. Unpublished data indicate that the drug reduces blood pressure in patients with type 2 (non-insulin-dependent) diabetes mellitus, without adversely affecting glucose homeostasis. Lercanidipine was well tolerated in clinical trials, with most treatment-related adverse events typical of dihydropyridine calcium antagonists, namely headache, flushing, dizziness and ankle oedema. CONCLUSIONS: Lercanidipine is an effective and well tolerated once daily antihypertensive agent in patients with mild to moderate hypertension. In addition, the drug may reduce BP when used as monotherapy in patients with severe hypertension or when used adjunctively in patients with resistant hypertension. Importantly, lercanidipine appears to be at least as effective and well tolerated as other commonly used antihypertensive agents. The drug therefore represents a useful therapeutic option in the management of patients with hypertension and will be particularly useful in patients not responding to, or intolerant of, antihypertensive agents from other drug classes.

Ropivacaine: an update of its use in regional anaesthesia.

UNLABELLED: Ropivacaine is a long-acting, enantiomerically pure (S-enantiomer) amide local anaesthetic with a high pKa and low lipid solubility which blocks nerve fibres involved in pain transmission (Adelta and C fibres) to a greater degree than those controlling motor function (Abeta fibres). The drug was less cardiotoxic than equal concentrations of racemic bupivacaine but more so than lidocaine (lignocaine) in vitro and had a significantly higher threshold for CNS toxicity than racemic bupivacaine in healthy volunteers (mean maximum tolerated unbound arterial plasma concentrations were 0.56 and 0.3 mg/L, respectively). Extensive clinical data have shown that epidural ropivacaine 0.2% is effective for the initiation and maintenance of labour analgesia, and provides pain relief after abdominal or orthopaedic surgery especially when given in conjunction with opioids (coadministration with opioids may also allow for lower concentrations of ropivacaine to be used). The drug had efficacy generally similar to that of the same dose of bupivacaine with regard to pain relief but caused less motor blockade at low concentrations. Lumbar epidural administration of 20 to 30ml ropivacaine 0.5% provided anaesthesia of a similar quality to that achieved with bupivacaine 0.5% in women undergoing caesarean section, but the duration of motor blockade was shorter with ropivacaine. For lumbar epidural anaesthesia for lower limb or genitourinary surgery, comparative data suggest that higher concentrations of ropivacaine (0.75 or 1.0%) may be needed to provide the same sensory and motor blockade as bupivacaine 0.5 and 0.75%. In patients about to undergo upper limb surgery, 30 to 40ml ropivacaine 0.5% produced brachial plexus anaesthesia broadly similar to that achieved with equivalent volumes of bupivacaine 0.5%, although the time to onset of sensory block tended to be faster and the duration of motor block shorter with ropivacaine. Ropivacaine had an adverse event profile similar to that of bupivacaine in clinical trials. Several cases of CNS toxicity have been reported after inadvertent intravascular administration of ropivacaine, but only 1 case of cardiovascular toxicity has been reported to date. The outcome of these inadvertent intravascular administrations was favourable. CONCLUSION: Ropivacaine is a well tolerated regional anaesthetic with an efficacy broadly similar to that of bupivacaine. However, it may be a preferred option because of its reduced CNS and cardiotoxic potential and its lower propensity for motor block.

Transdermal testosterone.

Nightly application of testosterone transdermal (TTD) system to nonscrotal sites in men with hypogonadism results in a 24-hour serum testosterone concentration profile which mimics the circadian pattern observed in healthy young men. The system also normalises dihydrotestosterone/testosterone and estradiol/testosterone ratios and reduces luteinising hormone levels towards the normal range. A multicentre, open-label study demonstrated that nocturnal erectile response and overall sexual function improved during 12 months' treatment with the TTD system (5 mg/day) in men with hypogonadism. Individual variables of sexual desire, arousal, frequency of sexual activity, orgasm and satisfaction also improved. The TTD system is well tolerated, with application site reactions such as pruritus, burn-like blisters and erythema being the most commonly reported events. Prostate-specific antigen levels and prostate volume remain in the normal range during long term treatment.

Trimetazidine. A review of its use in stable angina pectoris and other coronary conditions.

UNLABELLED: The orally administered antianginal agent trimetazidine increases cell tolerance to ischaemia by maintaining cellular homeostasis. In theory, this cytoprotective activity should limit myocyte loss during ischaemia in patients with angina pectoris. Data from studies in patients with coronary artery disease indicate that, unlike the effects of other antianginals, the anti-ischaemic effects of trimetazidine 20 mg are not associated with alterations in haemodynamic determinants of myocardial oxygen consumption such as heart rate, systolic blood pressure and the rate-pressure product. Furthermore, limited evidence suggests trimetazidine may improve left ventricular function in patients with chronic coronary artery disease or ischaemic cardiomyopathy and in patients experiencing acute periods of ischaemia when undergoing percutaneous transluminal coronary angioplasty. Clinical studies have shown that oral trimetazidine 20 mg 3 times daily reduces the frequency of anginal attacks and nitroglycerin use and increases exercise capacity when used as monotherapy in patients with angina pectoris. Its clinical effects are broadly similar to those of nifedipine 40 mg/day and propranolol 120 to 160 mg/day but, unlike these agents, trimetazidine does not affect the rate-pressure product during peak exercise or at rest. Adjunctive trimetazidine 60 mg/day reduces the frequency of anginal attacks and nitroglycerin use and improves exercise capacity in patients with angina pectoris not sufficiently controlled by conventional antianginal agents. Furthermore, the drug appears to be more effective than isosorbide dinitrate 30 mg/day when used adjunctively in patients with angina pectoris poorly controlled by propranolol 120 mg/day. The tolerability profile of trimetazidine 60 mg/day was similar to that of placebo when used as add-on therapy in patients with angina pectoris insufficiently controlled by other antianginal agents and was superior to that of either nifedipine 40 mg/day or propranolol 120 to 160 mg/day when used as monotherapy. The most frequently reported adverse events in trimetazidine recipients were gastrointestinal disorders, although the incidence of these events was low. CONCLUSIONS: Trimetazidine is an effective and well tolerated anti-ischaemic agent which, in addition to providing symptom relief and functional improvement in patients with angina pectoris, has a cytoprotective action during ischaemia. The drug is suitable for initial use as monotherapy in patients with angina pectoris and, because of its different mechanism of action, as adjunctive therapy in those with symptoms not sufficiently controlled by nitrates, beta-blockers or calcium antagonists. The role of trimetazidine in other coronary conditions has yet to be clearly established.

Perindopril 2mg/indapamide 0.625mg. Fixed low-dose combination.

Low-dose drug combinations have been proposed in International Guidelines for use in patients with hypertension. The fixed low-dose combination of perindopril 2mg with indapamide 0.625mg combines an angiotensin converting enzyme (ACE) inhibitor with a non-thiazide diuretic. Coadministration of perindopril and indapamide did not have any clinically significant effects on the pharmacokinetic profile of either agent in healthy volunteers. In experimental models of hypertension, perindopril/indapamide restored endothelial function, improved microvascular density, reduced left ventricular and aortic hypertrophy, and reversed renal end-organ damage. Once daily oral perindopril 2mg/indapamide 0.625mg normalised blood pressure (BP) in 83.6% of elderly patients with essential hypertension (diastolic BP was reduced to < or =90mm Hg) and 81.7% of those with isolated systolic hypertension (systolic BP was reduced to <160mm Hg) after approximately 1 year of treatment. BP normalisation was sustained in 79.8% of patients throughout the study. Fixed low-dose perindopril/indapamide had a tolerability profile similar to that of placebo in clinical trials; most adverse events were of mild to moderate severity. Coadministration of the 2 agents reduced the incidence of hypokalaemia seen with indapamide alone.

Candesartan cilexetil. A review of its use in essential hypertension.

UNLABELLED: Candesartan cilexetil is completely converted to the nonpeptide angiotensin II receptor blocker candesartan during absorption from the gastrointestinal tract. Candesartan selectively blocks and dissociates slowly from the angiotensin II subtype 1 (AT1) receptor which mediates most of the known activities of angiotensin II. When administered once daily, oral candesartan cilexetil 8 to 32 mg dose-dependently and effectively reduces blood pressure in patients with mild to moderate essential hypertension. In comparative studies, candesartan cilexetil 8 mg/day was as effective as usual therapeutic dosages of enalapril, losartan potassium, hydrochlorothiazide and amlodipine. One study showed candesartan cilexetil 16 mg/day to be more effective than losartan potassium 50 mg/day. Furthermore, the combination of candesartan cilexetil with either hydrochlorothiazide or amlodipine resulted in additive antihypertensive effects. Preliminary evidence suggests that the blood pressure-lowering effects of candesartan cilexetil are associated with the prevention or improvement of end-organ damage in patients with hypertension. However, this requires further confirmation in clinical studies. Candesartan cilexetil improves insulin sensitivity in patients with hypertension and does not affect glucose homeostasis or the serum lipid profile in those with coexisting type 2 (non-insulin-dependent) diabetes mellitus. Candesartan cilexetil is well tolerated in patients with hypertension. Pooled data indicate that the tolerability profile of the drug is not significantly different from that of placebo, with headache being the most commonly reported event. Adverse events are not dose related and are mostly mild to moderate in severity. Candesartan cilexetil is better tolerated than enalapril, primarily because of a reduced incidence of cough, and was not associated with the hypokalaemia or hyperuricaemia seen with hydrochlorothiazide in a study in patients aged > or = 75 years. The drug has an adverse events profile similar to that of losartan potassium in patients with mild to moderate hypertension. CONCLUSIONS: once daily candesartan cilexetil is effective and well tolerated when used once daily (as monotherapy or in combination with other antihypertensive agents) in patients with mild, moderate or severe hypertension. Initially, however, the drug is likely to be used as an alternative to other agents in patients not responding to or intolerant of their current drug therapy.

Telmisartan.

Telmisartan is a nonpeptide angiotensin II receptor antagonist which selectively and insurmountably inhibits the angiotensin II AT1 receptor subtype without affecting other receptor systems involved in cardiovascular regulation. Oral telmisartan dose-dependently reduced blood pressure (BP) in various animal models of hypertension. In transgenic rats, telmisartan reduced cardiac hypertrophy and glomerulosclerosis. When administered at dosages of 40 to 160 mg once daily to patients with mild to moderate hypertension, telmisartan significantly reduced systolic and diastolic BP compared with placebo and was at least as effective as atenolol 50 or 100 mg and lisinopril 10 to 40 mg. One study showed telmisartan 80 mg/day to be more effective than enalapril 20 mg/day. In 2 studies that used ambulatory BP monitoring, once daily telmisartan provided better control of diastolic BP for the full dosing interval than losartan potassium 50 mg or amlodipine 5 or 10 mg. In a single study in patients with severe hypertension, a telmisartan-based regimen had antihypertensive efficacy similar to that of an enalapril-based regimen. Telmisartan had a tolerability profile similar to that of placebo in clinical studies.

Tirofiban. A review of its use in acute coronary syndromes.

UNLABELLED: Tirofiban is an intravenously administered nonpeptide glycoprotein IIb/IIIa receptor antagonist which specifically inhibits fibrinogen-dependent platelet aggregation and prolongs bleeding times in patients with acute coronary syndromes. Adenosine diphosphate (ADP)-induced platelet aggregation returns to near-baseline levels within 4 to 8 hours after cessation of a tirofiban infusion, a finding consistent with the drug's elimination half-life of approximately 2 hours. Three large clinical trials have shown that, when administered with a standard heparin and aspirin regimen, tirofiban reduces the risk of ischaemic complications in patients with unstable angina/non-Q-wave myocardial infarction (MI) and in patients undergoing percutaneous revascularisation. In PRISM-PLUS, a study involving 1915 patients with unstable angina/non-Q-wave MI, administration of intravenous tirofiban (0.4 microgram/kg/min loading dose for 30 minutes followed by a 0.10 microgram/kg/min infusion) with heparin for at least 48 (mean 71.3) hours reduced the 7-day risk of the composite end-point of MI, death and refractory ischaemia by 32% compared with heparin alone. The between-group risk reduction remained significant at 30 days (22%) and 6 months (19%). Similarly, in high-risk patients undergoing coronary angioplasty in RESTORE, the addition of tirofiban (10 micrograms/kg bolus in the 3 minutes prior to intervention followed by 0.15 microgram/kg/min for 36 hours) to a standard heparin regimen significantly reduced the risk of ischaemic complications by 38% on day 2 and 27% on day 7 compared with heparin alone. Although interim analysis in PRISM-PLUS showed that the use of tirofiban without heparin increased the 7-day risk of death compared with heparin alone, this finding was inconsistent with the effects of tirofiban on the risk of death in PRISM, a study involving 3232 patients with unstable angina/non-Q-wave MI. Tirofiban is generally well tolerated. Bleeding complications were the most commonly reported events associated with tirofiban in clinical trials, but the rate of major bleeding in tirofiban recipients was not significantly different from that reported with heparin. Thrombocytopenia (platelet count < 90,000 cells/microliter) occurred slightly more frequently with tirofiban (with or without heparin) than with heparin alone. CONCLUSIONS: Tirofiban reduces the risk of ischaemic complications in patients with unstable angina/non-Q-wave MI and high-risk patients undergoing revascularisation when used against a background of heparin and aspirin. Furthermore, the drug has an acceptable tolerability profile. Therefore, intravenous tirofiban is likely to be used as an adjunct to heparin and aspirin in patients with acute coronary syndromes including high-risk patients undergoing revascularisation.

Valsartan/hydrochlorothiazide.

Valsartan/hydrochlorothiazide (HCTZ) combines an angiotensin II AT1 receptor blocker with a thiazide diuretic to produce additive blood pressure reductions without major effects on heart rate. HCTZ did not significantly alter valsartan pharmacokinetics; during combination therapy, HCTZ pharmacokinetics differed from those seen with HCTZ monotherapy. In clinical trials in patients with essential hypertension, adding HCTZ 12.5 or 25 mg/day to valsartan 80 mg/day resulted in a greater blood pressure reduction than increasing the valsartan dosage from 80 to 160 mg/day. The valsartan/HCTZ combination was generally more effective than either drug given alone. Efficacy of the combination was maintained during up to 3 years of treatment. Valsartan/HCTZ was well tolerated in both short and long term trials. The most common adverse events were dizziness, headache and fatigue. The overall incidence of adverse events with the combination was similar to that with placebo. HCTZ-induced hypokalaemia was less common during combination therapy.

Finasteride: a review of its use in male pattern hair loss.

UNLABELLED: The 5alpha-reductase inhibitor finasteride blocks the conversion of testosterone to dihydrotestosterone (DHT), the androgen responsible for male pattern hair loss (androgenetic alopecia) in genetically predisposed men. Results of phase III clinical studies in 1879 men have shown that oral finasteride 1 mg/day promotes hair growth and prevents further hair loss in a significant proportion of men with male pattern hair loss. Evidence suggests that the improvement in hair count reported after 1 year is maintained during 2 years' treatment. In men with vertex hair loss, global photographs showed improvement in hair growth in 48% of finasteride recipients at 1 year and in 66% at 2 years compared with 7% of placebo recipients at each time point. Furthermore, hair counts in these men showed that 83% of finasteride versus 28% of placebo recipients had no further hair loss compared with baseline after 2 years. The clinical efficacy of oral finasteride has not yet been compared with that of topical minoxidil, the only other drug used clinically in patients with male pattern hair loss. Therapeutic dosages of finasteride are generally well tolerated. In phase III studies, 7.7% of patients receiving finasteride 1 mg/day compared with 7.0% of those receiving placebo reported treatment-related adverse events. The overall incidence of sexual function disorders, comprising decreased libido, ejaculation disorder and erectile dysfunction, was significantly greater in finasteride than placebo recipients (3.8 vs 2.1%). All sexual adverse events were reversed on discontinuation of therapy and many resolved in patients who continued therapy. No other drug-related events were reported with an incidence > or =1% in patients receiving finasteride. Most events were of mild to moderate severity. Oral finasteride is contraindicated in pregnant women because of the risk of hypospadias in male fetuses. CONCLUSIONS: Oral finasteride promotes scalp hair growth and prevents further hair loss in a significant proportion of men with male pattern hair loss. With its generally good tolerability profile, finasteride is a new approach to the management of this condition, for which treatment options are few. Its role relative to topical minoxidil has yet to be determined.

Levobupivacaine.

Levobupivacaine is an enantiomer of the long-acting local anaesthetic bupivacaine, which, although currently the most widely used agent in surgery and obstetrics, is associated with potentially fatal cardiotoxicity. Levobupivacaine 75 to 122 mg was less arrhythmogenic than the same dose range of bupivacaine in healthy volunteers. Its effects on the corrected QT interval were significantly weaker than those of bupivacaine, and it tended to have a weaker effect on QRS duration. The CNS depressant effect of intravenous levobupivacaine 40 mg was less than that of bupivacaine 40 mg in healthy volunteers, both in terms of the magnitude of the effect and the regions of the cortex affected. Clinical studies have demonstrated that epidural levobupivacaine produces a sensory and motor block clinically similar to that of bupivacaine in patients requiring anaesthesia during surgery. However, the duration of sensory block was significantly longer with levobupivacaine 0.75% than with levobupivacaine 0.5% or bupivacaine 0.5% or 0.75% in one study. Levobupivacaine 0.25% was as effective as bupivacaine 0.25% in women requiring epidural anaesthesia during labour with respect to time to onset of pain relief, overall quality of analgesia, extent of sensory blockade and number of patients reporting motor block. Levobupivacaine is as well tolerated as bupivacaine. In a clinical study involving 88 patients who received either drug, intraoperative hypotension was the most commonly reported adverse event with levobupivacaine and no serious arrhythmias occurred.

Eprosartan.

Eprosartan is a nonpeptide angiotensin II receptor antagonist which has a high affinity for the AT1 receptor subtype. When administered at dosages of 400 to 800 mg/day (once or twice daily) for 13 weeks to patients with mild to moderate essential hypertension, eprosartan significantly reduced blood pressure compared with placebo. Eprosartan was at least as effective as enalapril 10 to 40 mg/day in a dose-titration study in patients with severe hypertension. Eprosartan is generally well tolerated; clinical trials have shown the drug to have a tolerability profile similar to that of placebo. As with other angiotensin II receptor antagonists, it does not cause cough. Eprosartan is not metabolised by the cytochrome P450 system and therefore has a low potential for drug interactions.

Dofetilide: a review of its use in atrial fibrillation and atrial flutter.

UNLABELLED: Dofetilide is a 'pure' class III antiarrhythmic agent which has demonstrated efficacy in the conversion of atrial fibrillation or flutter to sinus rhythm and the maintenance of sinus rhythm. By blocking the rapid component of the cardiac delayed rectifier potassium current (I(Kr)), dofetilide prolongs the cardiac action potential duration and the effective refractory period. This is thought to increase the likelihood of a re-entrant wavefront encountering refractory tissue and terminating the arrhythmia. Preliminary findings from the EMERALD (European and Australian Multicenter Evaluative Research on Atrial Fibrillation Dofetilide) and SAFIRE-D (Symptomatic Atrial Fibrillation Investigation and Randomized Evaluation of Dofetilide) studies suggest that oral dofetilide is effective in the conversion of atrial fibrillation or flutter to sinus rhythm. Both studies have yet to be published in full. In SAFIRE-D, dofetilide 500microg twice daily for 3 days achieved a conversion rate of 32% compared with a 1% rate for placebo. A similar conversion rate was achieved after 3 days in EMERALD with dofetilide 500microg twice daily (29%) which was significantly greater than that achieved with sotalol 80mg twice daily (6%; p < 0.05). Oral dofetilide also appears to be effective in the maintenance of sinus rhythm. An abstract report of EMERALD participants who had been converted to sinus rhythm showed that 71% of patients who received oral dofetilide remained in sinus rhythm after 6 months (compared with 26% of placebo and 59% of sotalol recipients: both p < 0.05). Restoration of sinus rhythm using intravenous dofetilide is more likely in patients with recent-onset versus prolonged-duration arrhythmia, and in those with atrial flutter rather than atrial fibrillation. Limitations of comparative data for intravenous dofetilide are such that few conclusions can be drawn. Although generally well tolerated in clinical trials, dofetilide has proarrhythmic potential. Torsade de pointes ventricular tachycardia was reported in up to 3.3% of patients who received oral dofetilide in the DIAMOND (Diamond Investigations of Arrhythmia and Mortality on Dofetilide) studies, although only a small proportion of patients in these studies had atrial fibrillation; most episodes occurred within the first 3 days. Whether the propensity of dofetilide for this life-threatening arrhythmia is similar to that of other class III antiarrhythmic agents has yet to be determined. Importantly, the long term use of oral dofetilide in patients at high risk for sudden cardiac death is not associated with an increased risk of mortality, although these DIAMOND findings cannot necessarily be extrapolated to patients with atrial fibrillation. CONCLUSIONS: Dofetilide offers an alternative to currently available antiarrhythmic agents for the pharmacological conversion of atrial fibrillation or atrial flutter to sinus rhythm and for the maintenance of sinus rhythm after cardioversion. However, further comparative data are necessary before its definitive place can be determined.

Fluvoxamine. An updated review of its use in the management of adults with anxiety disorders.

UNLABELLED: Fluvoxamine is a potent and selective serotonin reuptake inhibitor (SSRI) that has little or no effect on other monoamine reuptake mechanisms. Relative to other SSRIs, fluvoxamine is a weak inhibitor of cytochrome P450 (CYP) 2D6, a moderate inhibitor of CYP2C19 and CYP3A4 and a potent inhibitor of CYP1A2. In randomised, double-blind trials. fluvoxamine 100 to 300 mg/day for 6 to 10 weeks significantly reduced symptoms of obsessive-compulsive disorder (OCD) compared with placebo. Response rates of 38 to 52% have been reported with fluvoxamine, compared with response rates of 0 to 18% with placebo. In patients with OCD, fluvoxamine had similar efficacy to that of clomipramine and, in smaller trials, the SSRIs paroxetine and citalopram and was significantly more effective than desipramine. Maintenance therapy with fluvoxamine may reduce the likelihood of relapses in up to 67% of patients with OCD. Fluvoxamine < or = 300 mg/day for 6 to 8 weeks was as effective as imipramine in patients with panic disorder, and significantly more effective than placebo. In addition, treatment with fluvoxamine < or = 300 mg/day for > or = 8 weeks improved symptoms of social phobia (social anxiety disorder), post-traumatic stress disorder (PTSD), pathological gambling, compulsive buying, trichotillomania, kleptomania, body dysmorphic disorder, eating disorders and autistic disorder. Large trials comparing the efficacy of fluvoxamine and other SSRIs in patients with anxiety disorders are warranted. Fluvoxamine is generally well tolerated; in postmarketing studies, nausea was the only adverse event occurring in >10% of patients with less commonly reported events including somnolence, asthenia, headache, dry mouth and insomnia. Fluvoxamine is associated with a low risk of suicidal behaviour, sexual dysfunction and withdrawal syndrome. Fewer anticholinergic or cardiovascular events are associated with fluvoxamine than tricyclic antidepressants. Although comparative data are lacking, the tolerability profile of fluvoxamine appears to be broadly similar to those of other SSRIs. CONCLUSION: Fluvoxamine has demonstrated short term efficacy in the treatment of OCD, panic disorder, social phobia, PTSD and in a range of obsessive-compulsive spectrum disorders. The drug is as effective as clomipramine in patients with OCD but appears to have a better tolerability profile. On the basis of current treatment guidelines, fluvoxamine, like other SSRIs, is recommended as first-line treatment for a number of anxiety disorders. It appears to offer some pharmacokinetic advantages and a different drug interaction profile to the other SSRIs with a broadly similar spectrum of adverse events. However, direct comparisons are required to assess the relative efficacy and tolerability of the different agents of this drug class.

Dexmedetomidine.

Dexmedetomidine is a potent alpha2-adrenoceptor agonist with 8 times higher affinity for the alpha2-adrenoceptor than clonidine. Dexmedetomidine has shown sedative, analgesic and anxiolytic effects after intravenous administration to healthy volunteers or postsurgical patients in the intensive care unit. Dexmedetomidine produced a predictable haemodynamic decline (dose-dependently decreased arterial blood pressure and heart rate) in postsurgical patients coinciding with reductions in plasma catecholamines. In phase III clinical trials, dexmedetomidine 0.2 to 0.7 microg/kg/h produced clinically effective sedation and significantly reduced the analgesic requirements of postsurgical ventilated intensive care unit patients. There was no clinically apparent respiratory depression after cessation of assisted ventilation. Dexmedetomidine produced rapid and stable sedation in postsurgical ventilated patients while maintaining a high degree of patient rousability and anxiety reduction. Dexmedetomidine was well tolerated in phase III studies. The most frequently observed adverse events were hypotension, bradycardia and nausea.